It was inventory plus ease of use. Which is customer obsession.
One click purchase. Next day delivery. Flat fee shipping (prime). No questions asked drop-off returns. True, useful reviews. Good algorithmic sorting. Best in class logistics.
It was really much better than anything else online.
Now reviews are shit, searching products is a nightmare of sorting through clones and knockoffs, marketplace returns are hit or miss... and that's why it's worse.
At some point they got rid of that despite it being useful. I assume that Amazon prefers being able to control what you see when you search for an item. Now you’ll still see carousels and comparison tables when you click on an item, but it’s all stuff that vendors paid to have placed there (or that Amazon decided it wants you to see).
Maybe I'm misremembering but I don't remember this halcyon time where amazon was able to distinguish themselves from competitors to the consumer via anything but listed inventory. Their website has always been a cluttered mess filled with spam....